At 20:30 GMT today, people have been urged to switch off their lights for 60 minutes for Earth Hour. Now I realise this gesture is supposed to be symbolic rather than make a significant impact on the world’s annual energy consumption. I just hope it doesn’t send out the message that by switching lights off for an hour each year, it’s OK to do what you want for the rest of the time.

Sudden changes in electricity demand can cause problems for national power grids. Electricity has to be generated as it’s needed. If it isn’t planned for correctly, a sudden change in demand could in theory cause the national grid to “crash”, and lead to a blackout. Energy companies use complex models to forecast demand, and will also take into account occasions such as big sporting events, where television viewers will all put the kettle on at half time. So no doubt they are prepared for a drop in demand today. I suspect a trough is as much of a problem as a peak: how to deal with it? It might be necessary to take certain power stations offline, and restarting them can’t be that efficient. I’d be interested to know how much electricity, if any, Earth Hour actually saves when this is taken into account.

What would be far better for the Earth would be if people would think about switching lights off every day. I often despair at the number of lights left on at my workplace: in meeting rooms, kitchenettes, toilets, etc. despite those rooms not being in use. Every day I switch off several sets of lights as I walk past, often several times. I also can’t help but notice my neighbours, who seem to leave all the lights in their home on all the time, not just those in the room they are using.

So my suggestion would be to forget Earth Hour. If you want to register your views, take the time to write to elected representatives about it. Then make sure you always switch off lights in any rooms that are not in use – that will help not only the Earth, but also the electricity distributors!